A nice copy in contemporary, blind-ruled English calfskin, rebacked. The first title page is printed in red and black. Galileo’s “Sidereus Nuncius” and Kepler’s “Dioptrice” are introduced by separate title pages. The text is illustrated with astronomical woodcuts including images of the moon, showing its uneven, mountainous surface as discerned by Galileo through the telescope and four full-paged woodcut illustrations of stars (the Pleiades, Orion’s belt, the Praesepe and Orion Nebulas.)

Gassendi’s “Institutio Astronomica,” has been called the first modern astronomy textbook. It is divided into three sections: the first details the so-called theory of the spheres, the second describes astronomical theory, and the third discusses the conflicting ideas of Brahe and Copernicus. The present edition is important for the inclusion of two seminal works of telescopic astronomy: Galileo’s “Sidereus Nuncius” (first ed. Venice, 1610), in which announces his discovery of Jupiter’s moons, and Kepler’s “Dioptrice” (first ed. Augsburg, 1611), Kepler’s brilliant explanation of how the telescope works.Galileo’s Discoveries with the Telescope:”Galileo’s ‘Starry Messenger’ contains some of the most important discoveries in scientific literature. Learning in the summer of 1609 that a device for making distant objects seem close and magnified had been brought to Venice from Holland, Galileo soon constructed a spy-glass of his own which he demonstrated to the notables of the Venetian Republic, thus earning a large increase in his salary as professor of mathematics at Padua. Within a few months he had a good telescope, magnifying to 30 diameters, and was in full flood of astronomical observation.”Through his telescope Galileo saw the moon as a spherical, solid, mountainous body very like the earth- quite different from the crystalline sphere of conventional philosophy. He saw numberless stars hidden from the naked eye in the constellations and the Milky Way.

Above all, he discovered four new ‘planets’, the satellites of Jupiter that he called (in honor of his patrons at Florence) the Medicean stars. Thus Galileo initiated modern observational astronomy and announced himself as a Copernican. (Printing and the Mind of Man)

Kepler’s Explanation of the Telescope:”In order that the enormous possibilities harbored in the telescope could develop, it was necessary to clear up the theoretical laws by which it worked. And this achievement was reserved solely for Kepler. With the energy peculiar to him, inside of a few weeks, in the months of August and September of the same year, 1610, he composed a book tracing basically once and for all the laws governing the passage of light through lenses and systems of lenses. It is called ‘Dioptrice’, a word that Kepler himself coined and introduced into optics. […]”In problem 86 in which he shows ‘how with the help of two convex lenses visible objects can be made larger and distinct but inverted’ he develops the principle on which the astronomical telescope is based, the discovery of which is thus tied up with his name for all time. Further on follows the research into the double concave lens and the Galilean telescope in which a converging lens is used as objective and a diverging lens as eyepiece. By this suitable combination Kepler discovers the principle of today’s telescopic lens. Even this scanty account sows the epoch-making significance of the work. It is not an overstatement to call Kepler the father of modern optics because of it. (Max Caspar, “Kepler”, pp. 198-199) Kepler’s work is also the first to announce Galileo’s discovery that Venus has phases like the moon.